System and method of power line communication

ABSTRACT

Disclosed is a system and method for power line control of devices. The system operates in two modes. In mode one, the system operates on an open loop architecture with a controller generating a sinusoidal wave using a crystal oscillator. Control information is added to the sinusoidal wave by alternating the output of two phase shifted waves which have the same frequency and amplitude to form a control signal. The resulting control signal is sent on a power line. The control signal is received using a crystal filter, decoded and converted to executable instructions for the devices and data parameters for sensors. In mode two, the system operates on a hybrid open loop/closed loop architecture where devices are jointly controlled by the controller and the sensors.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND 1. Field

The present invention relates to a system and method of power linecommunication.

2. Background

Power line communication (PLC) to control devices and pass data is awell-known technology. Electrical power companies have used it since thefirst half of the twentieth century for telemetry and other selecteduses. Typically, a residential power line communication system operatesby modulating a carrier wave of between 20 and 200 kHz place on to thehousehold wiring by a transmitter. The modulation wave is typically adigital wave. The technology was adapted for use within commercial andhome settings in the 1970s with the development of X10, a narrowbandpower line communication system. As a system, X10 combined hardware,including transmitters and receivers, with a new transmission protocol.Since the carrier signal may propagate to nearby homes (or apartments)on the same distribution system, these control schemes have a “houseaddress” that designates the owner. Further, each receiver in the systemhas an address allowing each device including a receiver on the systemto be individually sent commands using signals transmitted over thehousehold wiring and decoded at the receiver. These devices may beeither plugged into regular power outlets, or permanently wired inplace. X10 generates 120 kHz bursts at the zero crossings of thealternating current power wave. X10 suffers from several drawbacks,primary among which was an inability to effectively send communicationsignals despite the electrical noise existing on power lines. The noisebeing introduced by devices connected to those lines for power. X10 alsohas transmission distance limitations due to the relative weakness ofthe signal, and the transmission signal suffers from phase changewhenever the signal crosses a terminal.

More recently, digital technology has been brought to bear on PLC. In1999, the Universal Powerline Bus (UPB), another narrowband power linecommunication system, was introduced. UPB uses pulse-position modulationto encode data on the power signal. Essentially, pulse-positionmodulation is a form of amplitude modulation. In pulse-positionmodulation, a pulse may be generated by the discharge of a capacitor inone of four positions in a frame placed toward the end of every halfcycle of the AC power wave. The position of pulse indicates a discreteinteger value from zero to three. Thus, the UPB protocol is capable ofgenerating two bits every cycle, and a byte every four cycles. Messagesin the protocol can be from 7 to 25 bytes. A major advantage of UPB wasthat the messaging protocol of UPB allowed for the “linking” of devices.With “linking” a single message could be sent, and the message couldinclude different commands, or the same command, for each device in thelink. In this way, multiple light fixture could be adjusted to aparticular scheme with one touch of a control.

UPB pulses are relatively weak in comparison to the AC power signal theyuse as a carrier wave. Certain devices or appliances generate electricalnoise in the same range as the power signal, which interferes with thepulse position modulation of the UPB system. One such device is a fan,which generates as much or more noise than most devices. The main sourceof electrical noise in a fan is the commutator brushes, which can bounceas the motor shaft rotates. This bouncing, when coupled with theinductance of the motor coils and motor leads, can lead to a lot ofnoise on the power line and can even induce noise in nearby lines. Thisnoise can interfere with system sensors and can even impair the systemmicrocontroller by causing voltage dips on the regulated power line.Large enough voltage dips can corrupt the data in microcontrollerregisters or cause the microcontroller to reset.

A number of potential solutions to the noise generated by fan motors andother devices have been proposed and implemented within UPB. Among theseare adding capacitors either across the fan motor terminals, or fromeach motor terminal to the case for grounding, keeping motor power leadsshort, and introducing filtering circuits. The filtering circuits may beplugged in to an outlet or hard wired in at an electrical panel. Each ofthese solutions either generates further problems that must be solved oris costly to implement in both equipment and labor.

There has been much work done recently in pulse modulating a carrierwave to send signals which convey information through phase shifting.However, extensive filtering of the signal is required, particularlywhen a user wished to create an ultra-narrow band signal. Theultra-narrow band signal can have as little as a single frequencybandwidth. High enough energy densities may allow for such a signal tobe used in powerline control, but there is no known way to ultra-narrowhand filter such modulations as baseband. Further, at the RF level, thefilters are complex and must be hand tuned. Finally, there is no knownway to build a zero group delay narrow band filer into a digital signalprocessing (DSP), finite impulse response (FIR) or infinite impulseresponse (IIR) filter.

Other attempts have been made at a broadband version of power linecommunication. Broadband over power line (BPL) is a system to transmittwo-way data over existing alternating current medium voltage (AC MV)electrical distribution wiring, between transformers, and alternatingcurrent low voltage (AC LV) wiring between transformer and customeroutlets (typically 110 to 240 V). Such systems, like allstate-of-the-art power line communication systems, do avoid the expenseof a dedicated network of wires for data communication, and the expenseof maintaining a dedicated network of antennas, radios and routers inwireless network.

BPL uses some of the same radio frequencies used for over-the-air radiosystems. Modern BPL employs frequency-hopping spread spectrum to avoidusing those frequencies actually in use, though early pre-2010 BPLstandards did not. The BPL OPERA standard is used primarily in Europe byinternet service providers. In North America, the BPL OPERA standard isused in some places (Washington Island, Wis., for example) but is moregenerally used by electric distribution utilities for smart meters andload management.

However, since the ratification of the IEEE 1901 (HomePlug) LAN standardand its widespread implementation in mainstream router chipsets, theolder BPL standards are not optimal for communication between AC outletswithin a building, nor between the building and the transformer where MVmeets LV lines. Deployment of BPL has illustrated a number offundamental challenges, the primary one being that power lines areinherently a very noisy environment. Every time a device turns on oroff, it introduces a pop or click, that is to say electrical noise, intothe line. Switching power supplies often introduces noisy harmonics intothe line. Devices such as relays, transistors, and rectifiers createnoise in their respective systems, increasing the likelihood of signaldegradation. Arc-fault circuit interrupter (AFCI) devices, required bysome recent electrical codes for living spaces, may also attenuate thesignals. Finally, transformers and DC-DC converters attenuate the inputfrequency signal almost completely. “Bypass” devices become necessaryfor the signal to be passed on to the receiving node. A bypass devicemay consist of three stages, a filter in series with a protection stageand coupler, placed in parallel with the passive device. And unlikecoaxial cable or twisted-pair, standard electrical wiring has noinherent noise rejection.

The second major issue is electromagnetic compatibility (EMC). Thesystem was expected to use frequencies of 10 to 30 MHz in the highfrequency (HF) range, used for decades by military, aeronautical,amateur radio, and by shortwave broadcasters. Power lines are unshieldedand will act as antennas for the signals they carry, and they will causeinterference to high frequency radio communications and broadcasting. In2007, the NATO Research and Technology Organization released a reportwhich concluded that widespread deployment of BPL may have a possibledetrimental effect upon military HF radio communications.

For the foregoing reasons, there is a need for a system which canprovide power line communication without detrimental effects from noiseand at sufficient data rates.

BRIEF SUMMARY

Disclosed is a system for controlling devices via power linecommunication. The system may include a controller which sends commandsindicative of a user's operation of the controller. The system mayfurther include a first transceiver, which may be electrically connectedto the controller. The first transceiver may include a firsttransmitter. The first transmitter may include a first crystaloscillator circuit. The first crystal oscillator circuit may include afirst crystal oscillator powered to transmit a sinusoidal wave at aclock frequency from a first output. The first transmitter may furtherinclude a second crystal oscillator circuit. The second crystaloscillator circuit may include a second crystal oscillator, which may bepowered to transmit a sinusoidal wave at a transmission frequency and afirst phase from a second output. The first transceiver may furtherinclude a signal splitter. The signal splitter may be connected to thesecond output. The signal splitter may split sinusoidal wave to a firstsignal and a second signal. The signal splitter may output the firstsignal to a third output and may output the second signal to a fourthoutput. A phase shift circuit may be connected to the fourth output andthe first output. The phase shift circuit may receive the second signaland phase shift the second signal to a second phase. The amount of phaseshift may be indexed by a ratio of the clock frequency to thetransmission frequency. The phase shift circuit may further include afifth output for outputting the second signal at the second phase. Thefirst transceiver may further include a switch. The switch may include afirst terminal, a second terminal, and a third terminal. The switch maybe electrically connected to the third output at the first terminal, thefifth output at the second terminal, and to a baseband signal outputtransmitting a baseband signal at the third terminal. The switch mayoperate to switch between alternately outputting the first signal andthe second signal as directed by the baseband signal. The outputcombination of the first signal and the second signal may form a controlsignal. The switch may further include a transceiver output on a commonof the switch for outputting the control signal. The system may furtherinclude a power line, which may be electrically connected to thetransceiver output. The system may further include one or moreelectrical outlets electrically connected to the power line. The systemmay further include one or more devices electrically connected to theone or more electrical outlets. The one or more devices may each includea second transceiver. The second transceiver may include a receiver. Thereceiver may include a ultra narrow band crystal filter which may filtera bandwidth centered around the transmission frequency. The one or moredevices may further include a baseband decoder, which may beelectrically connected to the ultra narrow band crystal filter. Thebaseband decoder may recover the baseband signal from the controlsignal.

Further disclosed is a method for providing power line communication.The method may include generating a sinusoidal wave using a crystaloscillator. The method may further include splitting the sinusoidal wavein to a first signal and a second signal. The method may further includephase shifting the second signal using a phase shift circuit. The methodmay further include outputting the first signal and the second, phaseshifted signal to a switch. The method may further include forming acontrol signal by operating the switch to alternate between outputtingthe first signal and the second, phase shifted signal according to abaseband signal, the first signal and the second, phase shifted signalimparting different phase states to respective portions of the controlsignal, the respective portions encoding binary information on thecontrol signal. The method may further include outputting the controlsignal to a power line. The method may further include receiving thecontrol signal on a receiver including an ultra narrow band filter, thereceiver being electrically connected to the power line. The method mayfurther include decoding the control signal to executable instructionsusing the protocol. The method may further include controlling theoperation of at least one device based on the decoded control signal.

Further disclosed is a system for providing power line communication.The system may include a smart device which may send commands which maybe created according to, and interpreted by, a protocol. The system mayfurther include a first transceiver electrically connected to the smartdevice. The transceiver may include a first crystal oscillatorgenerating a first signal sent to a first output. The system may furtherinclude a signal splitter connected to the first output. The signalsplitter may output the signal received from the first output to asecond output and may output a copy of the signal received from thefirst output to a third output. The system may further include a phaseshift circuit connected to the third output and including a fourthoutput, the phase shift circuit may be configured to shift the phase ofthe copy of the first signal. The phase shift circuit may output thesecond signal to the fourth output. The system may further include aswitch. The switch may have a first terminal which may be electricallyconnected to the second output and may have a second terminal which maybe electrically connected to the fourth output. The switch may furtherinclude a transceiver output. The system may further include a firstprocessor, which may be electrically connected to the smart device, theswitch, and to a first memory. The first memory may contain theprotocol. The first processor may execute the protocol according to thecommands from the smart device in order to generate a baseband signaloutput to the switch. The baseband signal may control the operation ofthe switch. The system may further include a power line. The power linemay be connected to the transceiver output. The system may furtherinclude at least one device, which may be electrically connected to thepower line. The at least one device may include a first receiverincluding a first ultra narrow band filter, a second processor, whichmay be electrically connected to the first ultra narrow band filter, anda second memory, which may be electrically connected to the secondprocessor. The second memory may contain a first copy of the protocol.The system may further include at least one sensor. The at least onesensor may be connected to the power line. The at least one sensor mayinclude a second transceiver. The second transceiver may include asecond receiver including a second ultra narrow band filter, and a thirdprocessor. The third processor may be electrically connected to thesecond ultra narrow band filter. A third memory may be electricallyconnected to the third processor. The third memory may contain a secondcopy of the protocol. When a user operates the smart device, a commandmay be sent. The protocol, executing on the first processor, may convertthe command to a control signal by sending a baseband signal to theswitch. The switch, according to the baseband signal, alternates betweenoutputting a first signal and a second signal in order to encode thecontrol signal with binary information. The control signal may be outputto the power line and may be received at the first ultra narrow bandfilter, second ultra narrow band filter, or both. The control signal maybe analyzed by the first copy of the protocol, second copy of theprotocol, or both. The decoded control signal may be executed on thesecond processor, or the third processor, or both. The control signalmay be converted to instructions for controlling the at least onedevice, or providing parameters for the at least one sensor, or both.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the various embodimentsdisclosed herein will be better understood with respect to the followingdescription and drawings, in which like numbers refer to like partsthroughout, and in which:

FIG. 1 shows a schematic diagram of an exemplary PLC system;

FIG. 2A shows a circuit diagram of one embodiment of the crystaloscillator and integrated circuit portions of the transceiver;

FIG. 2B shows a circuit diagram of one embodiment of the switch;

FIG. 2C shows a circuit diagram of one embodiment of a sub-circuit whichstrips harmonics from the signal output by the switch;

FIG. 3A shows a circuit diagram of the high frequency amplifier portionof the receiver of the transceiver;

FIG. 3B shows a circuit diagram of the amplifier and mixer portion ofthe receiver of the transceiver;

FIG. 3C shows a circuit diagram of the ultra narrow band filter of thereceiver;

FIG. 3D shows a circuit diagram of the amplitude limiting sub-circuit ofthe receiver;

FIG. 3E shows a circuit diagram of the baseband decoding sub-circuit ofthe receiver;

FIG. 4 shows a flowchart of a method of providing power linecommunication;

FIG. 5 shows a diagram of the two crystal oscillator waves at theswitch; and

FIG. 6 shows one embodiment of a detection method at the receiver.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of the presently preferredembodiment of system and method to control devices through powerlinecontrol, and is not intended to represent the only form in which it canbe developed or utilized. The description sets forth the functions fordeveloping and operating the system in connection with the illustratedembodiments. It is to be understood, however, that the same orequivalent functions may be accomplished by different embodiments thatare also intended to be encompassed within the scope of the presentdisclosure. It is further understood that the use of relational termssuch as first, second, distal, proximal, and the like are used solely todistinguish one from another entity without necessarily requiring orimplying any actual such relationship or order between such entities.

Disclosed is a system and method to control devices with control signalsand send data through a powerline. Control signals are sent via powerline communication to eliminate the need for a dedicated control cableinfrastructure as part of the system. The transmitter on a first end ofa powerline may be mirrored by a receiver at another end of a powerline.The receiver may be integrated with the device being controlled or maybe a separate component of the system placed between the device to becontrolled and the transmitter. Moreover, each of the transmitter andthe receiver may be combined to form a transceiver. Indeed, in mostembodiments, all such devices are transceivers. At least one transceiveron the system may further include circuitry which allows connection to awireless device

A controller may be electrically connected to the transceiver, which is,in turn, connected to the power line. The disclosed system may use abuilding's or even neighborhood's, or even region's pre-existingelectrical wiring infrastructure to send control signals. Sendingcontrol signals to control components of a system and transfer dataamong components is commonly called power line communication (PLC). Theuse of PLC completely eliminates the requirement for creating a cableinfrastructure separate from that of the power line in order to carrythe data and control signals. In the state-of-the-art non-PLC systemssuch signals are carried on an ethernet or RJ12 cable infrastructure, ortransferred wirelessly. The power line of a device or sensor may beconnected to one or more conventional outlets for providing power to thedevices or sensors. Each of the one or more outlets may have one or moresockets. One or more devices may plug in to one of the one or moresockets of each of the one or more outlets, thereby electricallyconnecting the devices to the power line. The power line may carry twoseparate signals. The first may be a power signal placed on to thepowerline by a power company. The second may be a control signal placedon the power line by the transmitter controlled by a user.

The system operates without the power signal acting as a carrier wave orthe power signal otherwise being changed in any way to conveyinformation. The power signal and the control signal are completelyseparate signals. The power signal is typically at 50 Hz or 60 Hz, butmay be at other frequencies, depending on the area of the world and theexisting power signal conventions there. However, the control signal mayhave a frequency in the kHz to double or triple-digit MHz range, or evenGHz range. Thus, while the two signals exist on the same line, they havelimited or no interaction.

The system may generate more than one a sinusoidal wave for use inencoding information. For example, the system may generate twosinusoidal waves at the same frequency and amplitude. The two sinusoidalwaves may be generated by two crystal oscillators or may be generated byone crystal oscillator and the signal split to form two signals. Togenerate each of the two sinusoidal waves, power may be applied to oneor more crystal oscillators. Each of the one or more crystal oscillatorsgenerate a constant sinusoidal wave in the high kHz to MHz range andwith a high Q factor. Importantly, when more than one crystal oscillatoris used, crystals of near identical construction may be used so that thecrystals generate signals of identical frequencies without a requirementfor frequency correction. The crystal oscillators may form part of alarger transmitter. A controller may be connected to the transmitter.One of the two sinusoidal waves may be phase shifted. Each of the wavesmay be assigned to represent a binary state.

Contemporaneously to the generation of the sinusoidal waves, a user maymanipulate the controller to send information to an electricallyconnected processor executing a protocol. The processor uses theprotocol to convert the information from the controller in to controlinformation to be encoded on the sinusoidal wave. In order to encodecontrol information using the two sinusoidal waves, the processor,according to the protocol, controls a switch which selectively choosesone or the other of the sinusoidal waves to be serially added to thepower line. The control information may be formed in to a basebandsignal, such as a digital wave. Thus, it is the switch that iscontrolled by the protocol, and specifically, the protocol using thebaseband signal, to encode the signal with information. One sinusoidalwave having a first phase may be used to represent either one or zero inthe protocol, and the second sinusoidal wave may represent the other ofthe one or zero. The timing of the switching, and thereby the placementand spacing of the phased waves, is done according to commandinformation sent from the controller which is then converted by theprotocol. The resulting signal with the encoded control information,called a control signal, is sent through the power line.

Once the control signal is output to a power line, the control signaltravels the extent of that power line, and any connected power lines.That is, the control signal will continue on the power line to everyterminal in a structure, or even beyond a structure, depending on thedesign of the power system and the PLC system. In this way, the controlsignal is broadcast on the power line.

On the receiving end, a device may be plugged in to a socket of the oneor more outlets. This electrically connects the device to the power lineand allows the device to receive both the power signal and the controlsignal present on the power line. On the device or an adapter placedbetween and connected to both the device and the power line, an ultranarrow band filter, as part of a receiver, may filter out all of thesignal on the power line except a bandwidth of, for example, 10 Hz orless centered on the transmission frequency of the crystal oscillators.Alternatively, the filter may allow more than a 10 Hz band to pass.Thus, the crystal filter acts as a bandpass filter, and filters only anarrow band centered on the transmission frequency, and allows the restof the signal to remain on the powerline. Once the control signal isreceived, the receiver may send the control signal to a processor foranalysis by the protocol and decoding back to baseband. The protocol maybe stored on a memory in the device or may be stored on the adapterelectrically connected to both the power line and the device. Accordingto the protocol, a determination may be made if the control signal isdirected to the device, if not, the control signal is ignored. If thecontrol signal is directed to the device, the protocol, executing on aprocessor, converts the control signal in to executable instructions forcontrolling the device. A single control signal transmission may includeone or more commands. When there is more than one command on the controlsignal, the commands may be the same command for different devices, ordifferent commands for the same device, or both.

Using this protocol, a single controller and transceiver combination cancontrol multiple individual devices on the system. All of this can beaccomplished without being affected by the electronic noise on the powerline. The system includes robustness against noise due to severalfeatures. First, the ultra-narrow bandwidth, which is at or approachingone Hertz, is only affected by noise which is on that specificfrequency. Relatedly, all the energy of the signal is placed on the samesingle frequency, resulting in a high energy density for the signal.Finally, the information on the signal is encoded by a very specificphase differential. One phase indicating a first binary state, and theother phase representing a second binary state. Unless the noiseincludes these specific phase changes, the signal may still be detected.

It may be possible for the devices to be controlled autonomously eitherby automated control signals sent by the controller, or by automatedcontrol signals sent from sensors, or both. Each device may have one ormore sensors electronically connected to it. In some embodiments of thesystem, the one or more sensors may be physically integrated with thedevice. When this is the case, the one or more sensors and the devicemay share a transceiver. When the one or more sensors are physicallyseparate from the device, for example, when one sensor may be assignedto control two or more devices and electronically connected to eachdevice the sensor is assigned to control. Each sensor may include atransceiver. When the sensor includes a transceiver, the sensor mayinclude instructions stored in a memory on the sensor which may beprogrammed by the controller. The instructions may be to change thestate of the device if certain criteria are detected by the sensor. Forexample, if the sensor is a temperature sensor and the device a light,and a first temperature is detected, the instructions may send a commanddimming the light. If a second temperature is detected by thetemperature sensor, the instructions may send a command for turning thelight off. The control signal is generated by the temperature sensor inthe same manner as the controller, except the commands are drawn from apredetermined list stored on a memory of the temperature sensor, andtriggered by conditions detected by the sensor, rather than beingtriggered manually as with a user's use of a smart device or controller.In addition, the controller may also have a list of automated commandsstored in memory. The commands may be triggered by conditions detectedby a connected sensor, or may be triggered by other conditions. Forexample, the command may be tied to a specific time, and the commandexecutes when the clock on the controller reaches that time.

More specifically, as shown in FIG. 1, the system 100 may include acontroller 102. The controller 102 may be electrically connected to atransceiver 104. The controller 102 may be a programmable logiccontroller which is connected to the transceiver 104 via a wiredconnection, for example, a low voltage wired connection as is well knownin the art. Alternatively, the transceiver 104 and the controller 102may be integrated in a single housing. Still further alternatively, orin addition, the controller 102 may be configured to allow controlfunctionality to be passed to an external device. For example, a devicerunning a software package available for personal computers withoperating systems such as Microsoft® Windows®, Mac® OS, Unix, Linux,etc. This configuration can allow a user to use a standard computer asan extension of the controller 102. Still further alternatively, a usermay use a mobile computing device 103 as an extension of, or in placeof, the controller 102. For example, Android®, iOS®, and Windows® basedmobile computing devices, such as smart phones and tablets can be usedas an extension of, or in place of, the controller 102. A user caninstall an application onto the mobile computing device 103. Theapplication can allow the mobile computing device 103 to function as anextension of, or in place of, the controller 102.

Regardless of what specific device is utilized as an extension of, or asthe controller 102, the user interface may communicate data to a routingdevice over a communication link. In one embodiment, the communicationlink can be a wireless communication link, for example, Wi-Fi,Bluetooth®, cellular (3G, 4G, 5G, LTE, etc.), or other suitable wirelesscommunication technology. Alternatively, the communication link could bea wired connection, such as Ethernet or other open and/or dedicatedcommunication protocols. The routing device can be a standard WiFi®local area network (LAN) router for receiving data, and then routing itto a device. The routing device may be integrated with the controller102.

A touch screen or a display (not shown) on the controller 102 orexternal computing device 103 may be used as a system interface by auser (not shown). Certain commands which may be executed by the protocolmay be indicated by control surfaces on the touch screen. For example,the commands may be indicated by icons or text, or a combination ofboth. When a user touches the portion of the screen with the controlsurface, a command is sent in a message to the processor in thetransceiver 104, which interprets the command using the protocol.

The transceiver 104 may include a transmitter portion 106 and a receiverportion 108. The primary function of the transceiver 104 is to sendsignals as directed by the controller 102 through the processor. Thetransmitter portion 106 of the transceiver 104 sends a signal upon whichcontrol information is encoded. The receiver portion 108 of thetransceiver 104 receives data signals from the devices or sensors. Forexample, the devices 130 a-h and the sensors may send acknowledgementsof messages or self-identification information to the transceiver. Forexample, devices may include an actuator, a fan, a light, a ballast fora light, a valve, a computer numerical controlled machine, a robot, aconveyor belt, or any other electrical or electrically controlleddevice.

As shown in FIGS. 1 and 2A, the transmitter portion 106 of thetransceiver 104 may include a crystal oscillator circuit 110. Thecrystal oscillator circuit 110 draws power from the power line 112. Thepower is taken from the power line 112 and may be transformed down by atransformer 138 a-j to a lower voltage. The power may also be convertedfrom alternating current to direct current. The voltage may betransformed down, for example, from 110V to 5 V. On a 0.2 A circuit ofthe power line 112, the 5 V of transformed voltage produces one watt ofpower for the crystal oscillator circuit 110. As shown in FIG. 2A, eachof two crystal oscillators may output a signal. The first crystaloscillator may have a first predetermined primary frequency andamplitude. The second crystal oscillator may have a second predeterminedprimary frequency and amplitude, with the second primary frequency beinga multiple of the first primary frequency. In the embodiment of FIG. 2A,one crystal oscillator produces a signal which is split to form the twosinusoidal waves for forming the control signal. The second crystaloscillator 160 provides a clock signal. The clock signal may be used tocontrol the amount of phase shifting. For example, if a crystaloscillator of 1 MHz is used to produce the signals for transmission, thecrystal oscillator for the clock signal may be a multiple of 4 MHz. Forexample, the crystal oscillator producing the clocks signal may be 16MHz. Based on the ratio, the transceiver may produce as many as 15 phaseshifted signals of the 1 MHz signal, using the 16 MHz clock signal, asis described in further detail below. One or more of the phase-shiftedsignals, along with the original signal, may be used to encodeinformation, as is described in further detail below. As long thecrystal oscillators receive power, the crystal oscillators will continueto output a signal.

Crystal oscillators emit a sinusoidal wave at a frequency determined bytheir physical structure. Importantly, crystal oscillators, andparticularly quartz crystal oscillators, have a very high Q factor.Quartz crystal oscillators are capable of primary frequencies from inthe high kHz up to the MHz range. However, higher frequency signals, upin to the GHz range, may be produced by amplifying a harmonic of theprimary frequency. Further, this disclosure also contemplates usingamplified harmonics of the oscillator, and even potentially frequencymodulated amplified harmonics, to allow transmission frequencies as lowas 1 Hz. Also, as indicated by the high Q factor, they have a narrowbandwidth relative to their frequency. A typical Q factor for a quartzoscillator ranges from 10⁴ to 10⁶, compared to 10² for an inductor andcapacitor, or LC, oscillator. The maximum Q for a high stability quartzcrystal oscillator can be estimated as Q=1.6×10⁷/f where f is theresonant frequency in megahertz.

Another important aspect of quartz crystal oscillators is that quartzcrystal oscillators exhibit very low phase noise. In many oscillators,any spectral energy at the resonant frequency is amplified by theoscillator, resulting in a collection of tones at different phases. In acrystal oscillator, the crystal mostly vibrates on one axis, thereforeonly one phase is dominant. Low phase noise makes crystal oscillatorsparticularly useful in applications requiring stable signals and veryprecise time references. This is particularly important with thisdisclosure as the signal from one of the crystal oscillators may bephase shifted by a precise amount. In an embodiment, for optimumoperation of the system, the phase shift between the two signals isconsistent, as is discussed below in greater detail.

A quartz crystal provides both series and parallel resonance. The seriesresonance is a few kilohertz lower than the parallel resonance. Crystalsbelow 30 MHz are generally operated between series and parallelresonance, which means that the crystal appears as an inductivereactance in operation, this inductance forming a parallel resonantcircuit with externally connected parallel capacitance. Any smalladditional capacitance in parallel with the crystal pulls the frequencylower. Moreover, the effective inductive reactance of the crystal can bereduced by adding a capacitor in series with the crystal. This lattertechnique can provide a useful method of trimming the oscillatoryfrequency within a narrow range; in this case inserting a capacitor inseries with the crystal raises the frequency of oscillation. For acrystal to operate at its specified frequency, the electronic circuithas to be exactly that specified by the crystal manufacturer. Note thatthese points imply a subtlety concerning crystal oscillators in thisfrequency range: the crystal does not usually oscillate at preciselyeither of its resonant frequencies.

Crystals above 30 MHz (up to >200 MHz) are generally operated at seriesresonance where the impedance appears at its minimum and equal to theseries resistance. For these crystals the series resistance is specified(<100Ω) instead of the parallel capacitance. To reach higherfrequencies, a crystal can be made to vibrate at one of its overtonemodes, which occur near multiples of the fundamental resonant frequency.Only odd numbered overtones are used. Such a crystal is referred to as a3rd, 5th, or even 7th overtone crystal. To accomplish this, theoscillator circuit may include additional LC circuits to select thedesired overtone.

Crystal oscillators may experience frequency drift over time. Thus, thesystem may include a frequency correction circuit to compensate for thisfrequency drift. The frequency modulation circuit may include an abilityto detect the incoming signal, and provide data on the frequency of theincoming signal to a processor. The processor may be connected to amemory which stores data on an expected frequency for the signal, andinstructions which may be executed on the processor to control thefrequency modulation circuit to modulate the incoming signal either upor down to match the expected frequency if the incoming signal is not atthe expected frequency. The frequency modulation circuit may extend theoperable life of the quartz crystal oscillator by compensating for theexpected eventual frequency drift.

As shown in FIGS. 1, 2A, and 2B, a signal from the first crystaloscillator circuit 111 is routed to an integrated circuit 162. Betweenthe first crystal oscillator circuit 111 and the integrated circuit 162,the signal may be split to create two signals. The signal may be splitat a location between the crystal oscillator circuit and the integratedcircuit 162. As shown in FIG. 2A, the crystal oscillator circuit may bea complimentary metal oxide semiconductor (CMOS) crystal oscillatorcircuit. Alternatively, the crystal oscillator circuit may be analternate type of oscillator circuit, with oscillator circuits whichoperate in series resonance being preferred. The split signal may beinput, each on a separate pin, to the integrated circuit 162. As shownin exemplary embodiment of FIG. 2A, the signal is input to theintegrated circuit 162 on two pins, pin A and pin B. The integratedcircuit 162 may include a phase shift sub-circuit 116 to phase shift oneof the input signals. It will be easily recognized by those of ordinaryskill in the art that the integrated circuit 162 may include a pluralityof phase shift sub-circuits in order to create a plurality of phaseshifted signals from at least one of the two input signals. At least oneof the two split signals input from the first crystal oscillator circuitto the integrated circuit 162 may pass through the integrated circuit162 without modification to the amplitude, frequency, or phase of thesignal. Moreover, all of the signals, including those that are phaseshifted, retain the same frequency.

The signals input on pin A may have a different signal path from thesignal input on pin B. For example, the signal input on pin B may passthrough a phase shift circuit, and the signal input on pin A passedwithout passing through a phase shift circuit. Alternatively, the signalfrom pin A may be phase shifted, and the signal input on pin B may passwithout the phase being changed. The integrated circuit 162 may phaseshift the second signal many times. For example, using the clock signalof 16 MHz to index the timing of the phase shifts of the 1 MHz signal,the signal may be phase shifted as many as 15 times. This is because16/1=16. That is, there are 16 possible phase states, or the originalstate and 15 shifted states in each cycle of the 1 MHz signal which areindexed by the 16 MHz clock signal. The 16 MHz clock signal is producedby a 16 MHz crystal oscillator circuit 160, and input to the clock pinof the integrated circuit 162. Thus, each of the 15 phase shiftedsignals may be shifted by 22.5 degrees because 360/16=22.5. As discussedabove, the frequency oscillation of a crystal oscillator is very stableand accurate. The phase shifting circuit of the present disclosure makesuse of this stability and accuracy of the clock frequency crystaloscillator, which is 16 MHz in the above example, as a tool in phaseshifting. Because the phase shift circuit indexes the phase shift basedon the stable and accurate frequency of the clock crystal oscillator,the phase shifts of the transmission frequency signal are very precise.This precision provides the potential for the use of multiple phasestates to create higher data rates.

As discussed above, there may be up to 16 different phase states in theexemplary embodiment. Depending on the crystals used, there may be morethan 16 or less than 16 possible phase states. Each of the phase statesmay be assigned to represent one of two binary states, that is, one orzero. While these phase states may be produced, the system may choose toutilize less than all the phase states that are produced. In thesimplest embodiment, the system may use just the unaltered signal andone phase shifted signal.

The phase shifted signal may then be routed to one terminal of a switch114. As shown in FIG. 2B, the switch 114 may be a combination of logicgates 115 a-d, for example not/and (NAND) gates, a fast switchingoperation, as is well known in the art, or any other switch which isable to provide fast enough switching, including transistors which mayact as switches by having a voltage applied to, and then disconnectedfrom, the base of the transistor. The switch may have the general effectequivalent to that of a single pole, dual throw, or SPDT switch. Thefirst of the two incoming signals from the first crystal oscillator maybe connected to a first terminal 164 of the switch 114. The second ofthe two incoming signals from the one or more crystal oscillators may beconnected to a second terminal 166 of the switch 114. The output may beconnected to the common of the switch 114. The speed of the switch 114allows for very rapid alternation between the first signal and the phaseshifted second signal. By way of example and not limitation, the switch114 may cycle fast enough to switch 10 times from the first signal tothe second signal and back to the first signal in a single cycle of a 40MHz signal. Thus, there is an opportunity, depending on the protocolused by the system, to send 10 bits of information in a single 40 MHzcycle, all without interference by noise. In this example, the systemcould generate 400 million bits of information a second on a bandwidthof a single frequency. Alternatively, the switch may cycle fewer than 10times in a 40 MHz cycle, or more than 10 times in a 40 MHz cycle. Stillfurther alternatively, the crystal oscillator may generate a sinusoidalwave at more than 40 MHz or less than 40 MHz. The operation of thesystem, including the creation and switching between the sinusoidalwaves produced by the crystal oscillators is discussed in great detailbelow. The transmission portion 106 is electrically connected to atransceiver output 120, which is in turn connected to the power line112. It will be apparent to one of ordinary skill in the art that thecomponents of the switch may be expanded to allow for the formation of acontrol signal with any plurality of phase states. While the exampleshown includes only two logic gates for the passage of the signals totwo phase states, one of ordinary skill in the art will recognize thatthe exemplary configuration of FIG. 2B can be expanded to accommodatemany more phase states. For example, even 100 or more phase states maybe possible. When designing an embodiment for a plurality of phasestates to encode information on a control signal, a balance may bestruck between the frequency of the transmission signal and the numberof phase states. For example, when lower frequencies are used, morephase states may be used, and when higher frequencies are used, fewerphase states may be used. This is only a general rule, and other factorsmay cause exceptions.

As shown in FIG. 2C, before the control signal is transmitted, thecontrol signal may be routed through a harmonic elimination andfrequency mixing circuit 121. The circuit may include a plurality ofcrystal oscillators 123 a, 123 b, 123 c, 123 d and capacitors 125 a, 125b, 125 c, 125 d in parallel. The control signal passes through onecapacitor 127 in series, and then through a transistor 168. Finally, thecontrol signal passes through a signal lamp 170 and is output.

The transceiver 104 may include a memory 122 on which a protocol isstored, and a processor 124 which is electrically connected to thememory, and on which the protocol is executed. The protocol may includea portion which interprets commands sent by the controller 102, or froma transceiver 126 a-i in a device 130 a-h or a sensor 131 a. Theprotocol, executed by the processor 124, accomplishes the encoding ofthe output of the crystal oscillator circuit by controlling the switch114 through a baseband signal.

The protocol is designed so that control signals include an identifieras to which device 130 a-h or sensor 131 a, 131 b the message isdirected. If a message is not directed to a particular device 130 a-h orsensor 131 a, 131 b, that device or sensor ignores the message.

The power line 112 may carry standard North American domestic power.That is, 120 V nominal, 60 Hz electrical power. As noted previously, thepower line may have electronic noise on it from one or more sources.Alternatively, the voltage may be more than 120V or less than 120V.Further alternatively, the frequency of the power signal may be greaterthan 60 Hz or less than 60 Hz.

The power line may be carrying single phase or three phase power. If oneor more of the three phase conductors are split to provide single phaseoperation, the disclosed system will still function, because the outputroutes the control signal to each of the conductor wires on athree-phase system, rather than selectively choosing just one.

One or more devices 130 a-h or one or more sensors 131 a, 131 b, orboth, may be connected to the power line 112. In FIG. 1, 8 devices 130a-h are shown, but it will be understood that there could be fewer than8 devices, or more than 8 devices. The devices 130 a-h include a plug(not shown) for connecting the device 130 a-h to a conventional outletsocket 132 a-h on a conventional outlet. The conventional outlet 132 a-his electrically connected to the power line 112. The devices 130 a-hfurther include a transceiver 126 a-c, and 126 e-i to receive thecontrol signal from the transceiver 104 or a sensor 131 a and 131 b whena sensor is not integrated with the device, as is the case with sensor131 b and device 130 e, a processor for executing the protocol, a memoryfor storing the protocol, and a transmitter for sending bothself-identification information, and acknowledgement messages to thetransceiver, and a transformer which takes power from the power line forpowering the temperature sensor, transceiver and the memory andprocessor which executes the protocol.

As shown in FIGS. 1, and 3A-3E, the transceiver 126 a-i in the devices130 a-h and sensor 131 a includes a receiver. The receiver includes aplurality of sub-circuits. As shown in FIG. 3A, a received controlsignal may first pass through a high frequency amplification sub-circuit302 of the receiver. As shown in FIG. 3B, a mixing and amplificationsub-circuit 304 may be connected to the high frequency amplificationsub-circuit 302. As shown in FIG. 3C, connected to the mixing andamplification sub-circuit 304 is an ultra narrow band filter 306. Theultra narrow band filter 306 passes a very narrow band of frequencies,for example, 10 Hz. Just as with the crystal oscillator in thetransceiver 104 and transceivers 126 a-i, the crystal in the ultranarrow band filter 306 has a very high Q factor. The crystal's stabilityand its high Q factor allow ultra narrow band filters 306 to haveprecise center frequencies and steep band-pass characteristics. Thus,the ultra narrow band filter only captures frequencies in anultra-narrow band centered on the frequency produced by the crystaloscillator circuit 110 and does not allow the rest of the signal on thepower line to pass to the transceiver. Thus, the power signal on thepower line may be routed to other components in the device to providepower, with the power signal being substantially unaffected. As shown inFIG. 3D, the ultra narrow band filter 306 is connected to an amplitudelimiting sub-circuit 308. A control signal passing through the amplitudelimiting sub-circuit has the amplitude controlled because too highamplitude in the control signal can cause distortion in the controlsignal when the control signal is decoded. As shown in FIG. 3E, theamplitude limiting sub-circuit 308 may be connected to a basebanddecoding sub-circuit 310. As explained in further detail below, in thebaseband decoder sub-circuit 310 may receive the analog signal withvarying phase states, and the protocol may be used to measure the phasestates against a clock signal as a standard or index. The basebanddecoding sub-circuit 310 uses one or more integrated circuits 312, 314to convert the control signal in to a binary baseband signal. Afterconversion, the decoded baseband signal is amplified by an operationalamplifier 316 and output.

This configuration of the crystal oscillator in the transceiver 104 andcrystal filter in the transceiver 126 a-i of the device 130 a-h plays alarge role in eliminating noise. In some systems, noise has been aproblem which prohibits the use of PLC. Solutions to the electricalnoise problem have been proposed, but all are either burdensome, orcostly, or both. For example, a broadband filter may be added to thesystem to filter out the noise, but the equipment is expensive andbulky, and often required to be wired to a structure's electrical panel.Such solutions merely place post installation band aids on the problem.

The disclosed system does not suffer from electronic noise interferingwith the control signal for several reasons. First, the frequency atwhich the configuration operates is relatively high as compared to thepower signal on the power line. In the case that the noise does reachthe frequency of the control signal, the noise would have to be equalto, the power of the control signal to compete in the ultra-narrowbandwidth. The ultra-narrow bandwidth is another aspect of the systemwhich provides robustness against noise. The electronic noise would haveto be found within the bandwidth, which, were the bandwidth relativelywide, would be likely. However, with the bandwidth so narrow, it isrelatively unlikely that electronic noise will be found within theultra-narrow bandwidth. Moreover, for example, with a one-watttransmission power spread across a very small bandwidth, which may beeven a single frequency, the control signal can compete with, if notoutright overmatch, most noise. Also, the noise would have to be inphase with both of the crystal oscillator-produced signals. Even if thenoise were to be at the same frequency and have the same power as thecrystal oscillator produced signals, the control signal may bedetectable within the noise unless the noise includes both of the phasestates of the control signal. It is extremely unlikely that the noisewill include both phase states or change phase as rapidly as the controlsignal.

Another benefit of the disclosed system and method is the distance overwhich the control signals of the disclosed system can be transmitted.Because the energy of the control signal is spread across a muchnarrower bandwidth than typical electromagnetic signals conveyingcontrol information, the control signal does not suffer from attenuationin the way that a broader bandwidth signal with the same energy would.As a result, the signal travels over a longer distance than a similarlypowered signal with a greater bandwidth. As with most other electricalsignals, lower frequency signals travel farther.

Such a transceiver 104, device 130 a-h, and sensor 131 a and 131 bconfiguration has still further advantages. Because the system 100operates on such a narrow bandwidth, the system does not interfere withother devices or systems. Moreover, because of the signal's placement inthe spectrum, there are very few devices with which the system 100 caninterfere. Thus, the system 100 is not only able to deal with the worstnoise found on most power lines 112 but is further able to avoidinterfering with other systems because the system 100 operates on anultra-narrow bandwidth.

Sensors, for example, sensor 131 b, may be integrated with each of thedevices. When integrated, the sensor may share the device's transceiver126 f with the device. Alternatively, the device and sensor may share atransceiver, memory and processor. Still further alternatively, thedevice and the sensor may each have a dedicated transceiver, memory, andprocessor. Thus, during operation, all commands may be sent directly tothe device and stored in the device's memory for processing by theprotocol on the processor, and accessed by the device or sensor, orboth.

Alternatively, the sensors may be separate, but electrically connectedto the device. Depending on the configuration and characteristics of thedevice, the device may interfere with the data taking function of thesensor, necessitating physical separation. Moving the sensor away fromthe device may allow for more accurate or effect data taking, or bothmore accurate and effective data taking.

The sensor may be a component separate from the device. The sensor maybe connected to the powerline. The memory electrically connected to thesensor may store parameters sent by the controller for a correspondingset of commands already saved to a memory of the sensor. The sensor unitmay include a power supply which includes a plug to connect to an outletsocket in order to send and receive control signals. The plug alsoallows the sensor unit to receive a power signal. The power supply mayinclude transformers to decrease the incoming voltage to properly powerthe components of the temperature sensor unit.

When the sensor is separate from the device, each sensor includes atransceiver identical to that of the transceiver operating inconjunction with the controller. The sensor may include instructionsstored in a memory on the sensor which may have certain parameters ofcommands set by the controller. For example, the controller may set aparticular temperature as a parameter. Based on the temperature, theremay be a command to dim the device, for example, a light fixture, or ata different and higher temperature, to turn the light fixture off. Thecontrol signal is generated by the sensor, for example, a temperaturesensor, in the same manner as a control signal is generated by thecontroller, except the commands are drawn from a predetermined list ofcommands stored on the memory of the sensor, and triggered by conditionsdetected by the sensor. For example, a temperature sensor may have acommand to turn off a device, specifically a light fixture, if atemperature of 95 degrees Fahrenheit is detected by the sensor. Thus,rather than the commands being determined manually, the commands aredetermined autonomously based on predetermined conditions.

It may also be the case that a system, which may include light fixturesamong multiple kinds of devices, uses a combination of the above sensorconfigurations, which may be, for example, a sensor for temperaturealone, or may be a combination sensor which includes a temperaturesensor among several kinds of sensors which can detect several kinds ofdata. That is, some light fixtures may have a temperature sensorintegrated with the light portion, other light fixtures on the systemmay have a temperature sensor integrated with the ballast, and stillother light fixtures may be controlled by a separate temperature sensoras an individual component of the system.

Regardless of whether a single type of device and sensor arrangement isused, or a combination of types of device and sensor arrangements areused, all of the device and sensor arrangements are directed toachieving the purpose of decentralization of sensing and control. Asdescribed above, prior art systems all have centralized sensing andcontrol. With as much as one sensor for every device, much more precisecontrol can be achieved because the sensor may provide localized controlfor the device in a closed loop fashion, completely apart from thecontrol provided by the main controller.

The disclosed PLC system may operate as a hybrid system. That is the PLCsystem may simultaneously operate as both an open loop system withportions of subsystems operating as a closed loop system. Any device maybe controlled both by the controller in open loop, and by the assignedsensor, if any, in closed loop. It should be noted, however, that theprotocol is designed such that the controller and sensors do not sendthe same commands at the same time. Rather, control may be split betweenthe two depending on which of the controller and sensor is bestpositioned to issue the command.

The disclosed system, both because of the method of control, and becauseof the physical arrangement of the components of the system, offersconsiderable robustness against failures. A device in the disclosedsystem will continue to function under the control of both, or either,of the controller and the assigned sensor should any other device in thesystem cease functioning. Depending on the location and type of failurein a pure open loop system, the entire system may cease functioning.Further, if the sensor is integrated in to the device, even multiplefailures elsewhere in the system may not affect the flow of commandsfrom the sensor to the device. Even if the sensor is a separatecomponent, there may be a very short distance of powerline between thedevice and the sensor. The copper wire of the powerline on which thesignals are carried has very low failure rates, making a failure of thewire between a sensor and a device highly unlikely. Thus, even with alonger span of wire between the controller and any devices than theremay be between a sensor and a device, failures of the wire are veryunlikely. Because the commands may be sent from either the sensor or thecontroller, total failure of the system is highly unlikely. Even in theevent of the failure of the controller or an individual sensor, thecontroller or other sensors will still operate devices assigned to thosesensors. Almost all sensors also have extremely low failure rates,making the most likely source of failure the controller. However,failures of the controller are easier to detect than any other failureon the system, for reasons explained below. This lowers the risk of theoperation of the system.

As noted above, the transceiver 104 includes both a transmitter 106, anda receiver 108. The transmitter 106 includes the combination of thecrystal oscillation circuit 110, and the switch 114. The receiver 108 ofthe transceiver 104 is the same as the receiver 126 a-i described forthe devices 130 a-h and the sensor 131 a. Further, the transmitterintegrated with device and sensor transceivers 126 a-i is the same asthe transmitter 106 described for the transceiver 104 operating inconjunction with the controller. The transceiver 126 a-i on the devices130 a-h and sensor 131 a may be used to send acknowledgements ofcommands sent to the devices 130 a-h and sensors 131 a, 131 b back tothe transceiver 104. The receiver 108 on the transceiver 104 may be usedto receive identification information from the devices 130 a-h andsensors 131 a, 131 b which are electrically connected to the transceiver104, the controller 102, or both. Further, the receiver 108 on thetransceiver 104 may be used to receive the acknowledgements from thedevices 130 a-h and sensors 131 a, 131 b. For example, when a sensor 131a is a component of the system separate from a device, the sensor 131 amay include a transceiver 126 d. The transceiver of the sensor isidentical to that of the transceiver operating in conjunction with thecontroller and the transceiver integration with a device.

In operation, the system may function in two distinct modes, but themodes may operate in parallel, or contemporaneously. The first mode maybe characterized by control signals being sent exclusively from thecontroller. The second mode may be characterized by essentiallyautonomous control of the devices by the system's sensors, andsecondarily, autonomous control signals from the controller. That is, itis possible that the controller and the sensors may send control signalscontemporaneously, or even almost simultaneously. The two modes areprimarily distinguished by user control in the case of signals from thecontroller and autonomous control based on predetermined parametersstored in the sensors and controller. In the case of the first mode,after the controller 102 is powered up, woken up from sleep mode, orconnected via a wired or wireless connection to the transceiver 104, thecontroller 102 may interrogate the devices 130 a-h and sensors 131 a,131 b electrically connected to the power line 112. This is done by thecontroller 102 sending a command to the devices 130 a-h and sensors 131a, 131 b to respond to the command with identification information. If acontroller 102 is already connected, the protocol may require that adevice 130 a-h or sensor 131 a, 131 b which is later connected to thesystem 100 send self-identification information to the controller 102.

Because the controller 102 is able to identify each device 130 a-h orsensor 131 a, 131 b, or combination thereof, connected to the controller102 individually, future commands may be specified as being for aparticular device 130 a-d, 130 f-h or separate sensor 131 a orcombination device/sensor 130 e/131 b. Because these commands containinformation identifying the device 130 a-d, 130 f-h or separate sensor131 a, or combination device/sensor 130 e/131 b to which they aredirected, the commands will be ignored by other devices or sensors, orcombination device/sensor. Alternatively, some or all of the devices 130a-d, 130 f-h or separate sensors 131 a, or combination device/sensor 130e/131 b could be specified by a command. Thus, groups of devices, forexample, a group of light fixtures in a specified area of a structure,may be controlled as a group. Alternatively, the separate sensors may becontrolled as a group apart from the devices, or vice versa. Or, if, forexample, all devices and separate sensors need to be powered down, thiscan also be accomplished through the above identification of all devices130 a-h and separate sensors 131 a, or combinations thereof. In fact,there may be a particular identifier in the protocol specifying that acommand is for all components of the system, including devices 130 a-h,separate sensors 131 a, and combinations thereof. Such an identifierprevents the protocol from requiring that each device 130 a-h and sensor131 a, if any are separate components, have an individual identifierseparately listed in a command.

In order to send commands to one or more devices 130 a-h with integratedsensors, or to separate sensors operating in mode one, commands from thecontroller 102 are converted to control signals by the protocol. Thecontrol signal has two parts. The first part is a first sinusoidal wave,which is generated continuously by one or more crystals in one or morecrystal oscillation circuits, as shown in Step 410 on FIG. 4. The secondpart is a second sinusoidal wave which is generated either by the sameone or more crystal oscillation circuits or another of the one or morecrystal oscillation circuits. This second sinusoidal wave is then phaseshifted so it is out of phase with the first sinusoidal wave. The twosinusoidal waves may be out of phase, for example, by 22.5 degrees.Alternatively, the first sinusoidal wave and the second sinusoidal wavemay be out of phase by as less than 22.5 degrees or more than 22.5degrees. As shown in FIG. 5, the non-phase shifted sinusoidal wave 510,and the phase shifted sinusoidal wave 512, are electronically routed toa switch. Using the switch controlled by the protocol, controlinformation may be encoded on an output signal. The information may beencoded by creating an output wave which alternates between the firstsinusoidal wave and second sinusoidal wave according to a basebandsignal which is input to the switch 114 from a processor. The output ofthe switch 114, which is shown in Step 420 of FIG. 4, includes portionsof the two signals which are in two different phases. The portions maybe in series. Thus, the first sinusoidal wave may form a section of thecontrol signal, and be followed by a section formed by the secondsinusoidal wave, and vice versa. Alternatively, as is discussed above,there may be a plurality of phase states, for example, 16. Each of thephase states may be assigned to represent one of the two binary states,and in the exemplary embodiment of 16, provide 16 bits of data per cycleof the transmission frequency. After generation, each of the sinusoidalwaves may be fed to the connected switch 114, as is described above. Theswitch 114 is also connected to a processor 124 which executes theprotocol. Based on the command signals from the controller, which areconverted by the processor to a baseband signal using the protocol, theprocessor 124, using the baseband signal, directs the switch 114 toswitch between the first sinusoidal wave and the second sinusoidal wave.Information is encoded on the output sinusoidal waveform by varying thetiming between the first sinusoidal wave and the second sinusoidal wavefrom the crystal oscillator circuit 110 by switching the switch 114 fromthe first signal to the second, phase shifted signal and back to thefirst signal, and back again, in order to encode the information carriedby the baseband signal. The phase shifting allows one of the signals, orsinusoidal wave, to represent a first binary state, for example zero.The second signal, or sinusoidal wave, may represent a second binarystate, for example one, or vice versa. The spacing of portions of thewave having a certain phase may represent control information as well.For example, if a portion of the output signal is twice as long asanother portion, the first portion may represent two of the first binarystates in a row. All of the above encoding may be decoded by theprotocol when the output signal is received by the receiver. The outputwave including the control information may be called a control signal.

As discussed above, the timing for the portions of a signal of a certainphase may be set to a fractional portion of the wave cycle of thecrystal oscillator frequency by the protocol. For example, the controlsignal may be timed so that a portion of the signal is never any lessthan a full cycle. Thus, where a signal of a first phase 510 appears onthe output wave, the protocol may interpret the first phase 510 asindicative of a first binary state, while uninterrupted, addition cyclesrepresenting additional instances of the same binary state. When theoutput wave changes phase to a second binary state 512, a cycle of thesecond phase may be indicative of a second binary state. In thisembodiment of the encoding one phase is assigned a binary state, andalways indicates that binary state.

Alternatively, a change in phase may represent a first binary state,while no change in phase from, for example, cycle to cycle, representsanother binary state. It is contemplated that the phase may change moreoften than a single cycle, and less often than a single cycle. It is thechange of cycle, or, as in the previous embodiment, the presence of acertain phase that is indicative of the binary states. Single cycles areused as examples herein to make the operation of the system easier tounderstand, but one of ordinary skill will instantly recognize thatthere is no requirement to use whole cycles for operation of the system.In this second embodiment, a change is indicative of a first binarystate. Thus, after a first cycle, the phase may change. The change maybe indicative of a binary state, for example one. The phase remainsunchanged for another cycle. This lack of change may be indicative of asecond binary state, for example, zero. Thus, two different phase statesmay seem to represent different binary states, but, in reality, it isthe presence or absence of change between phases that represent thedifferent binary states.

In either of the above protocol definitions, the protocol may interpretthe control signal as a series of binary states, with the binary statesrepresenting either a one or a zero. Commands may be defined by theprotocol from differing sequences of ones and zeros, or binarysequences.

Sequences of ones and zeros may form data or commands that can beanalyzed and converted by the protocol. Therefore, the sequences of onesand zeros may be said to form a baseband signal. As an example, thedevices and separate sensors may identify themselves using a binary codeof a set number of digits. The identification may be a shorter or longersequence than those of the commands. The protocol may define apreliminary indicator which indicates the start of a command or datastring, and a second indicator which indicates the command or data sendis complete and requests that the device or sensors to which the commandwas directed send an acknowledgement to the controller. Similarly, theprotocol may use binary sequences to define commands. Each of these maybe included in the baseband signal. By way of example and notlimitation, the protocol may define that “1001” may correspond to acommand to turn a device 130 a-k, to 100% of any adjustable range. Forexample, if the device is a light, that means turning on the light tomax brightness, or if the device is a fan, turning that fan on to maxrevolutions per minute. A control signal of “1000” may correspond to acommand to turn the device 130 a-k off. The data and commands may bepackaged as messages that include the preliminary indicator that acommand or data follows, headers which identify to which fans thecommand is directed, the command, and an indicator that the command iscomplete and a request for acknowledgement of the command by the deviceor sensor.

It is important to note that when the first sinusoidal wave and secondsinusoidal wave are combined in serial segments to create the controlsignal, the frequency of the first and second sinusoidal waves areunaffected. That is, the frequency of the control signal is that same asthat of the first sinusoidal wave and second sinusoidal wave. Rather,only the phase changes within the control signal when the firstsinusoidal wave and second sinusoidal wave are combined in segments tocreate the control signal. Thus, the control signal is output to thepower line with the frequency unaffected.

Once the control information is encoded by using the switch to alternatethe sinusoidal waves generated by the crystal oscillator circuit 110,the control signal is output to the power line 112 as is shown in Step430 of FIG. 4. The output is a broadcast throughout the power line 112.An exemplary control signal 150 is shown in FIG. 6. The control signal600 includes a plurality of phases 610, 612. It will be noted that thesegments of differing phases 610, 612 are placed at protocol-definedintervals along the control signal 600, rather than one phase changeafter another with no space in between, which would make detectionextremely difficult with current detector technology, although suchspacing is still theoretically possible.

Alternatively, the transceiver may include additional circuitry whichmay either be bypassed or may receive an output of the signal of thetransmission crystal oscillator. This circuitry may be configured toamplify a harmonic frequency of the signal output by the transmissioncrystal oscillator. For example, the harmonic may be an order ofmagnitude higher in frequency than the resonant frequency of thetransmission crystal oscillator. Other harmonics and the primaryfrequency may then be stripped from the signal. This amplified andhigher frequency signal may then be split and encoded as describedabove. Further, the smart device or controller may have a setting whichindicates which devices and which sensors are close and which are at adistance. The higher frequency may be used for faster response andhigher data rates where possible, and the lower frequency signal may beused for devices and sensors which are out of range of the higherfrequency transmission, ensuring the control signal is received by thedevices and sensors at a greater distance.

Start up control signals may be sent using mode one operation by thecontroller, and may include power on signals for designated devices. Thepower on signals may be refined predetermined modifications. Forexample, in the case of a device with a range of settings, for example,a light, the predetermined modification may ramp up the brightness ofthe light produced by the light fixtures during power on. The same maybe done during power off by including a predetermined modificationramping down the brightness of each light fixture during power off.Ramping up and ramping down may use the dimming function of the lightsto gradually power them on from a lower brightness to a greaterbrightness, and gradually power the lights down from a greaterbrightness to a lower brightness, and then off. These predeterminedmodifications may be of great benefit when the lighting system is usedfor indoor agriculture, because the ramping simulates sunrise andsunsets, allowing the lighted crops to receive the same type of lightthey would if the crops were in an outdoor environment. Alternatively,all of the above control signals may come from the controller duringboth mode one and mode two of the operation of the system.

Commands or parameters may also be sent using mode one to the sensors,without regard to whether the sensors are integrated with a device orare separate components on the system. For example, the controller maysend data parameters for the sensor's native commands. For example, ifthe sensor is a temperature sensor, the sensor may include a dimmingcommand. The dimming command may specify dimming to a lower wattage whena temperature parameter is met. By way of example and not limitation,the controller may specify that the temperature sensor should send adimming command to the light to 50% of the current wattage if atemperature of 80 degrees Fahrenheit is detected by the sensor. Thesensor may further include a shutdown command. The shutdown command mayturn off the light fixture if the sensor assigned to the light detects atemperature indicated in by parameter sent by the controller. By way ofexample and not limitation, if the temperature parameter sent by thecontroller is 90 degrees Fahrenheit, and the sensor detects atemperature of 90 degrees Fahrenheit, the sensor may send a command tothe lighting fixture to shut down. If the sensor is a separate componentof the system, the controller may send control signals to the sensorassigning devices to which the sensor is to send control signals.Because the controller is sent identification information by all thesystem components, a user may identify the components and make theassignment using the controller. Alternatively, the controller mayinclude algorithms which assign sensors to devices automatically.

On the receiving end, the control signal 600 is received on thereceiving circuit 108. After being amplified, the control signal ispassed to the ultra narrow band filter of the device transceiver 126 a-kor sensor transceiver, if sensors are implemented as separate componentson the system, as is shown in Step 440 of FIG. 4. The ultra narrow bandfilters may operate to bandpass a bandwidth of 20 Hz or less centered onthe transmission frequency of the crystal oscillator from the signal onthe power line. Naturally, the rest of the signal on the power line maybe unaffected so that the power on the power line may be used to powerdevices and sensors on the system. The 20 Hz or less bandwidth capturesthe control signal because the phase changes do nothing to spread thebandwidth of the original sinusoidal wave generated by the crystaloscillator. That is to say, the signal is not frequency modulated.Alternatively, the filter may pass a bandwidth of well than 20 Hz ormore than 20 Hz.

Following the filtering, the protocol stored on a memory 123 a-h, andexecuting on a processor 127 a-h on each of the devices 130 a-h, theprotocol stored on a memory 123 a-h, and executing on a processor 127a-h on each of the devices, the protocol stored on a memory 134 a, 134b, and executing on a processor 136 a, 136 b on each of the sensors, orintegrated device and sensor, detects and analyzes the information inthe control signal 150. The control information encoded on the controlsignal 150 may be decoded and converted by the protocol as is shown inStep 450 of FIG. 4. Based on where the detected phase states, and thetiming of the control signal in each phase state, the control signal maybe converted to a series of binary digits, or a series of ones andzeros. The conversion may then be used to determine instructions whichare executable to give commands to the devices and to set parameters forthe sensors, either integrated with the devices or as separatecomponents, as is shown in Step 460 of FIG. 4, and described above.Alternatively, the center point may be defined in the positive portionof the cycle or the negative portion of the cycle. Alternatively, ifonly two phase states are used, the detector may detect unchanged, orbase phase state signals, and assign a first binary state to thosesignals, as required by the protocol, and assign a second binary stateto any other signals which have differing phase states. If multiplephase states are used, then each may be assigned one of the two binaryphase states, and the detector may determine at which phase state thesignal is located, and assign a binary state to that signal detected atthat particular phase state according to the protocol.

The use of ultra-narrow bandwidth and phase changes to encode data andunaltered frequency sinusoidal wave in the control signal providesfurther robust protection against interference by electrical noise onthe power line 112. In order for electrical noise on the system tointerfere with the control signal the electrical noise would need bothreach in to the narrow bandwidth on which the oscillator istransmitting, and the filter is receiving, and to change phase as thecontrol signal 600 does. This kind of rapid phase change combined with afixed amount of offset is uncommon in electrical noise, including thenoise typically found on power lines. Thus, in addition to all the otherways the system 100 eliminates electrical noise which may affect thecontrol signal 600, even the manner in which the information is encodedto the control signal 600 provides robustness against interference byelectrical noise.

After the control signals are sent and received, the system mayprimarily operate in mode two. Mode two is characterized by acombination of open and closed loop operation, but relies primarily onmode two operation. As described above, the sensors may send commandsignals using the same encoding as the control signals from thecontroller. However, no user direction is required when mode two signalsare sent by sensors. Based on the parameters provided during mode one,each sensor may automatically send control signals to the assigneddevices if any of the stored parameters are reached. Per the examplegiven above for the temperature parameters, if the temperature sensordetects a temperature of 80 degrees Fahrenheit, the temperature sensormay send a control signal containing a dimming command to thetemperature sensor's assigned light fixtures. Alternatively, if thetemperature sensor detects a temperature of 90 degrees Fahrenheit, thetemperature sensor may send a control signal containing a shut-downcommand to the temperature sensor's assigned light fixtures. Allcommands which have a temperature as a parameter may be native to thetemperature sensor, with the controller providing the parameter of theprecise temperature at which the commands should be sent during phaseone.

Simultaneously during mode two operation, the controller may still sendcommands which include time as a parameter. The controller 102 includesa clock function, which may be set to local time. The controller mayalso include a timing function to control when the devices are poweredon and when they are powered off. This function is particularly usefulin indoor agriculture, because when sent to lights, it allows the lightsto simulate daylight during a 24-hour day cycle. The timing functionincludes sending a control signal to the one or more light fixtures topower on at a predetermined time, and to power off at a predeterminedtime. The powering on may be customized by ramping the brightness of theone or more light fixtures up to simulate a sun rise, as describedabove. Similarly, the powering off may be customized by ramping thebrightness of the one or more light fixtures down to simulate a sun set,which is also described above. Both the ramping time, and the startingbrightness, as well as the amount of increase in wattage, and thereforeresulting brightness, may be parameters which may be set by a user.These parameters may be built in to the controller and will operateessentially autonomously during phase two. As one of ordinary skill inthe art will readily recognize, such parameters may be applied to otherdevices as well. For example, the timing may be used to control asprinkler system, or a residential or commercial HVAC system.

Of course, the parameters for either the controller or the sensor may bechanged at any time by a user. This may be necessary for any number ofreasons, but is not required unless there is a component failure.Failure detection is discussed in detail below.

The devices 130 a-h or sensors 131 a, 131 b may, contemporaneously toany control signals from the controller 102, send an acknowledgement ofthe control signal back to the controller 102, or to the sensor if thesystem is in mode two operation. The receiver portion of the transceiver104 or the transceiver on the sensor receives the acknowledgement, theprocessor on either of the transceivers converts it using the protocol,and, accordingly, the controller 102 or the sensor does not resend thecommand. In the event that the transceiver 104 or the transceiver on thesensor does not receive the acknowledgement, the protocol operating onthe controller 102 or sensor directs the corresponding transceiver tosend the command again after a pre-determined time interval. Thispattern continues until the acknowledgement is received from the device130 a-k or sensor to which the control signal was sent.

In some circumstances, it may be possible that the device did not sendan acknowledgement because the device never received the message. Forexample, if system is operating in the two or three-digit MHz range orhigher, and the signal has to travel through any appreciable distance ofwire, the signal may be attenuated by the wire, or by other factors, andnot reach the device. In some embodiments the system may have a secondset of crystal oscillators which operate at a lower frequency. Theinstructions stored in memory may include that the next message be sentusing this lower frequency. Lower frequency signals generally havebetter range in every medium. This is also true in the case ofelectrical wire. Thus, if the initial control signal failed to reach thedevice, the lower frequency signal is all but guaranteed to reach thedevice. Thus, if the device fails to respond to the control signal,sending an acknowledgement back to the transceiver operating inconjunction with the controller, or the transceiver associated with asensor, the user can be all but certain that the reason is that thedevice is suffering a failure, rather than the signal failing to reachthe device. Thus, the device can be checked and serviced in such aninstance. If the transceiver operating with the controller receives aacknowledgement from the transceiver associated with the device, thenthe transceiver operating with the controller will continue tocommunicate with the device on the lower frequency.

Alternatively, the crystal oscillator circuit may include componentswhich allow access to harmonics of the crystal. The crystal oscillatorcircuit may use a lower frequency harmonic of the crystal rather than asecond crystal to generate the lower frequency control signal. Theharmonic may be amplified to a level equivalent to that of thenon-harmonic signal. In either this embodiment or the previousembodiment, the entire system may switch to operate on the lowerfrequency. Alternatively, the controller and transceiver with which itoperates may continue to communicate at both frequencies, depending onthe device with which it is communicating. Those devices that don'trespond on the primary, higher frequency signal, but do respond to thesecondary, lower frequency signal, will continue to communicate on thelower frequency signal, both for control signals and acknowledgements.This split frequency system has the advantage of ensuring communicationwith as many devices as possible while using higher frequencies wherepossible to give the data rates for the maximum possible number ofdevices on the system.

Should the controller 102 fail catastrophically, the controller 102 willno longer send commands. While this is certainly a failure, it is notcatastrophic for the system as a whole, because such a controllerfailure is both easy to detect, and the devices on the system maycontinue to function under the control signals available to the one ormore sensors on the system. A controller 102 failure is easy to detectbecause the controller 102 is typically used by the user to sendcommands from time to time, and may further automated commands, asdescribed above. A user is likely to notice if automated commands arenot executed. Thus, if, for example, the system includes lights, and allof the lights fail to turn on or off, there is likely a failure in thecontroller.

As disclosed, through the decentralized control, the lighting system hasinternal robustness against the risk of a failure of a centralcontroller. The one or more sensors on the system will continue tofunction. In embodiments where the one or more sensors includeinstructions to issue control signals to the devices on the system, thesensors will continue to do so. Thus, if, for example, the lights on asystem are not turned off due to a controller catastrophic failure, thetemperature may get high enough where the temperature may be detrimentalto the plants of an indoor agricultural system. However, even if thecontroller 102 has failed, the one or more temperature sensors may dimthe lights as the first predetermined temperature is reached, and thenmay shut the lights off as the second predetermined temperature isreached. In this way, the decentralized control prevents damage to theplants. If the light fixtures don't come back on, the controller 102failure is again easily detected and rectified by replacing thecontroller and starting back up.

It may be possible that, over time, each of the crystal oscillators mayhave some drift in the transmission frequency. The crystal oscillatorcircuit may include portions which are directed to correcting for anyfrequency drift. The crystal oscillator circuit may include componentswhich allow the transmission frequency to be tuned. The tuning may bedone manually, through adjustments of the circuit by a user.Alternatively, the crystal oscillator circuit may include componentswhich monitor the transmission frequency and adjust the transmissionfrequency automatically back to a pre-determined transmission frequencyif there is any drift detected.

Alternatively, or in addition, the crystal filters may be tuned. Similarto the crystal oscillation circuit, the crystal filter may be tunedmanually or automatically. For example, if the transmission frequency ofthe transceiver operating with the controller beings to drift, thetransmission frequency may be adjusted to match where it was previously,so that only a single transceiver has to be adjusted, and not several.Alternatively, the crystal filters may be tuned to match the driftedsignal of the controller transceiver. As a still further alternative,both the controller transceiver may be tuned. For example, either thecontroller transceiver or the device transceiver may be automaticallytuned. For example, the crystal filter may include an auto centerfunction where the crystal filter scans a bandwidth of possiblefrequencies, and when it finds a transceiver signal, centers on thatsignal.

The above description is given by way of example, and not limitation.Given the above disclosure, one skilled in the art could devisevariations that are within the scope and spirit of the inventiondisclosed herein, including various ways of defining the commands in theprotocol. Further, the various features of the embodiments disclosedherein can be used alone, or in varying combinations with each other andare not intended to be limited to the specific combination describedherein. Thus, the scope of the claims is not to be limited by theillustrated embodiments.

What is claimed is:
 1. A system for controlling devices via power linecommunication, comprising: a controller which sends commands indicativeof a user's operation of the controller; a first transceiverelectrically connected to the controller, the first transceiverincluding a first transmitter, including: a first crystal oscillatorcircuit including a first crystal oscillator powered to transmit a firstsinusoidal wave at a clock frequency from a first output; a secondcrystal oscillator circuit including a second crystal oscillator poweredto transmit a second sinusoidal wave at a transmission frequency and afirst phase from a second output; a signal splitter connected to thesecond output, the signal splitter splitting the second sinusoidal waveto a first signal and a second signal and outputting the first signal toa third output and the second signal to a fourth output; a phase shiftcircuit electrically connected to the fourth output and the firstoutput, the phase shift circuit receiving the second signal and phaseshifting the second signal to a second phase, the amount of phase shiftbeing indexed by a ratio of the clock frequency and the transmissionfrequency, and the phase shift circuit including a fifth output foroutputting the second signal at the second phase; a switch including afirst terminal, a second terminal, and a third terminal, the switchelectrically connected to the third output at the first terminal, thefifth output at the second terminal, and to a baseband signal outputtransmitting a baseband signal at the third terminal, the switchoperating to switch between alternately outputting the first signal andthe second signal as directed by the baseband signal, the outputcombination of the first signal and the second signal forming a controlsignal; a transceiver output on a common of the switch for outputtingthe control signal; a power line electrically connected to thetransceiver output; one or more electrical outlets electricallyconnected to the power line; one or more devices electrically connectedto the one or more electrical outlets, the one or more devices eachincluding: a second transceiver including a receiver, the receiverincluding an ultra narrow band filter which filters a bandwidth centeredaround the transmission frequency; and a baseband decoder electricallyconnected to the ultra narrow band filter, the baseband decoderrecovering the baseband signal from the control signal.
 2. The method ofclaim 1, further comprising at least one sensor.
 3. The method of claim2, further comprising a processor electrically connected to each of theat least one sensor, and a memory electrically connected to theprocessor.
 4. The method of claim 3, further comprising a thirdtransceiver electrically connected to the at least one senor and locatedbetween the sensor and the power line.
 5. The method of claim 4, whereinone of the at least one sensor sends control signals to only one of theone or more devices.
 6. The method of claim 5, wherein the one of the atleast one sensor sends control signals to the only one of the one ormore devices based on parameters sent to the sensor by the controller.7. The method of claim 1, wherein the baseband decoder interprets afirst phase state of the control signal as a first binary state and asecond phase state of the control signal as a second binary state.
 8. Amethod for providing power line communication, comprising: generating asinusoidal wave using a crystal oscillator; splitting the sinusoidalwave in to a first signal and a second signal; phase shifting the secondsignal using a phase shift circuit; outputting the first signal and thesecond signal to a switch; forming a control signal by operating theswitch to alternate between outputting the first signal and the second,phase shifted signal according to a baseband signal, the first signaland the second, phase shifted signal imparting different phase states torespective portions of the control signal, the respective portionsencoding binary information on the control signal; outputting thecontrol signal to a power line; receiving the control signal on areceiver including an ultra narrow band filter, the receiver beingelectrically connected to the power line; decoding the control signal toexecutable instructions using the protocol; and controlling theoperation of at least one device based on the decoded control signal. 9.The method of claim 8, wherein the phase of the signal wave is shiftedaccording to an index of a clock frequency generated by a clock crystaloscillator and electrically connected to the phase shift circuit, and atransmission frequency of the first signal and the second signal. 10.The method of claim 8, wherein the phase shift circuit is part of anintegrated circuit.
 11. The method of claim 8, wherein the controlsignal may include information for one or more sensors connected to thepower line.
 12. The method of claim 11, wherein the information mayinclude parameters for the operation of the sensor.
 13. A system forproviding power line communication, comprising: a smart device whichsends commands which are created according to, and interpreted by, aprotocol; a first transceiver electrically connected to the smartdevice, the transceiver including a first crystal oscillator generatinga first signal sent to a first output; a signal splitter connected tothe first output and outputting the first signal from to a second outputand a copy of the first signal to a third output; a phase shift circuitelectrically connected to the third output and including a fourthoutput, the phase shift circuit configured to shift the phase of thecopy of the first signal, creating a second signal with a phase statedifferent from that of the first signal, the phase shift circuitoutputting the second signal to the fourth output; a switch having afirst terminal electrically connected to the second output and a secondterminal electrically connected to the fourth output, the switch furtherincluding a transceiver output; a first processor electrically connectedto the smart device, the switch, and a first memory containing theprotocol, the first processor executing the protocol according to thecommands from the smart device in order to generate a baseband signalwhich is output to the switch, the baseband signal controlling theoperation of the switch; a power line connected to the transceiveroutput; at least one device electrically connected to the power line,the at least one device including a first receiver including a firstultra narrow band filter, a second processor electrically connected tothe first ultra narrow band filter, and a second memory electricallyconnected to the second processor, the second memory containing a firstcopy of the protocol; and at least one sensor connected to the powerline including a second transceiver, the second transceiver including asecond receiver including a second ultra narrow band filter and a thirdprocessor electrically connected to the second ultra narrow band filter,a third memory electrically connected to the third processor, the thirdmemory containing a second copy of the protocol; wherein, when a useroperates the smart device to send a command, the protocol, executing onthe first processor, converts the command to a control signal by sendinga baseband signal to the switch, the switch, according to the basebandsignal, alternates between outputting the first signal and the secondsignal in order to encode the control signal with binary information,the control signal being output to the power line and received at thefirst ultra narrow band filter, second ultra narrow band filter, orboth, analyzed by the first copy of the protocol, second copy of theprotocol, or both, executed on the second processor, or the thirdprocessor, or both, and converted to instructions for controlling the atleast one device, or providing parameters for the at least one sensor,or both.
 14. The system of claim 13, wherein the first transceiverfurther includes a circuit which compensates for frequency drift of thefirst crystal oscillator.
 15. The system of claim 13, wherein the atleast one sensor sends control signals based on the parameters.
 16. Thesystem of claim 13, wherein the at least one device and the at least onesensor send an acknowledgement to the controller after receiving acontrol signal.
 17. The system of claim 13, wherein the firsttransceiver can output at a first frequency and a second frequency, thefirst frequency being an order of magnitude or more higher than thesecond frequency.
 18. The system of claim 17, wherein the secondfrequency is a harmonic of the first frequency.
 19. The system of claim17, wherein the first receiver and the second receiver can receive onboth the first frequency and the second frequency.
 20. The system ofclaim 13, wherein the at least one device and the at least one sensorinclude a transmitter, the transmitter including a crystal oscillationcircuit for sending acknowledgement messages.